This is pretty crazy- the rear window on my wife's '04 Sequoia stopped rolling down a year or so ago. I finally got around to researching a fix and found this TSB, along with forum posts indicating that there may be nothing wrong with the window motor, that just removing a couple of parts and a spring (item 14) would fix the problem. So I dug into the window regulator, removed the parts and spring, and voila- window works like it was new. I couldn't figure out what the parts did, either. They bolted up and put tension on part of the regulator, but not much at all. Its like Toyota put these things in by mistake, and the TSB fixes their mistake. Go figure.
http://ww2.justanswer.com/uploads/skyvisions/2008-02-25_151840_01_seq.pdf
http://ww2.justanswer.com/uploads/skyvisions/2008-02-25_151840_01_seq.pdf